Variable pitch excavator dipper mounting



March 29, 1966 r. LEARMONT 3,243,053

VARIABLE PITCH EXCAVATOR DIPPER MOUNTING Filed Jan. 7, 1965 4 Sheets-Sheet 1 I l 34' *WQWV 1| 49 I5 38 I 1; 4-6 3 .99 w 44' 4 1 ,5 i lf i I III II x 4 3e. 34 T 38 w Z2 1 49 INVE'NTOR TOM LEARMONT ATTORNEY March 29, 1966 T. LEARMONT 3,243,053

VARIABLE PITCH EXCAVATOR DIPPER MOUNTING Filed Jan. 7, 1965 4 Sheets-Sheet 2 INVENTOR TOM LEARMONT ATTORNEY March 29, 1966 T. LEARMONT 3,243,063

VARIABLE PITCH EXCAVATOR DIPPER MOUNTING Filed Jan. 7, 1965 4 SheetsSheet 5 56 INVENTOR 5s 57 55 TOM LEARMONT :ZmM/MW ATTORNEY March 29, 1966 T. LEARMONT 3,243,053

VARIABLE PITCH EXCAVATOR DIPPER MOUNTING Filed Jan. '7, 1965 4 Sheets-Sheet 4 United States Patent 3,243,063 VARIABLE PITCH EXCAVATOR DHPER MOUNTING Tom Learmont, Milwaukee, Wis., assignor to Bueyrus- Erie Company, South Milwaukee, Wis., a corporation of Delaware Filed Jan. 7, 1965, Ser. No. 423,935 9 Claims. (Cl. 214-137) This invention relates to excavator dipper mountings, and particularly to an excavator dipper that is pivotally connected substantially centrally of its rear wall to the end of a dipper handle with extensible and retractable power actuating means connected between the dipper handle and the dipper above and below the pivotal connection, and which power actuating means are actuable to vary the pitch of the dipper relative to the dipper handle as desired for efiicient digging and dumping.

There exists a trend toward utilizing larger size dippers on power shovels and other excavators without proportional increases in the size of the dipper handle, boom, A-frame and other structural elements. This has been made possible by improvements in materials and design. However, the use of larger size dippers results in a proportion of dipper size to dipper handle which often yields an ineflicient pitch or angle of approach of the dipper to the bank of material being excavated. That is, the height of the front wall of the dipper, to which the dipper teeth are attached, is of such a large dimension relative to the length of the dipper handle, and therefore the swing radius of the dipper in a vertical plane, that during digging the dipper may not be properly inclined for the most eflortless entry into the bank or for the complete filling of the dipper as the dipper moves through the bank. Obviously, the inability to fully use the available capacity of the dipper detracts from the advantages normally accruing by the mounting of larger size dippers on existing equipment.

Additionally, in all power shovels regardless of the size of the dipper relative to the swing radius, it is desirable to position the dipper vertically during dumping of its contents. The load will be allowed to fall cleanly out of the dipper if the interior surfaces of the side and front walls of the dipper are disposed vertically. However, in the normal fixed mounting of excavator dippers on the dipper handles the dipper must be raised to an unreasonable height before the dipper will be disposed vertically and at such elevation a considerable portion of the dumped load can miss a dump truck.

Accordingly, it is a principal object of this invention to provide an excavator dipper mounting in which the pitch of the dipper may be varied relative to the dipper handle for most efiicient digging and dumping.

It is a further object of this invention to provide such an excavator dipper mounting in which the dipper may be pivoted through a vertical plane about the dipper handle as the dipper moves through the bank to be excavated.

In a variable pitch dipper mounting according to this invention, the dipper is pivotally mounted substantially centrally of the top and bottom of its rear wall to the dipper handle. Extensible and retractable actuating means are connected between the dipper handle and the dipper at points above and below the pivotal mounting of the dipper. A control system is employed for selective actuation of the actuating means to cause the dipper to pivot about the pivotal mounting on the dipper handle and thereby present the desired pitch of the dipper for digging or for dumping.

The mounting of the dipper on the dipper handle and the connection of the actuating means is such that the effect of loads, and particularly torsional loads, on the actuating means is minimized.

3,243,063 Patented Mar. 29, 1966 In the preferred embodiment of the invention, the actuating means take the form of pressure responsive cylinders and pistons that are hinged at one end on the dipper handle rearwardly of the pivotal connection to the dipper and at the other end on the rear wall of the dipper. The cylinders and pistons are powered during both their extending and retracting strokes so that all cylinders and pistons operate to tilt the dipper.

It is another object of this invention to provide a variable pitch dipper mounting including actuating means operable to vary the pitch of the dipper relative to the dipper handle, and which dipper is so mounted to the dipper handle and the actuating means so disposed relative to the dipper mounting as to minimize the effect of normal and shock loads on the actuating means.

It is also an object of this invention to provide such a variable pitch dipper mounting in which pressure responsive cylinders and pistons are disposed above and below a central pivot connection of the dipper to the dipper handle, and in which both the cylinders and pistons above and below the pivotal connection are operable to tilt the dipper either upwardly or downwardly about the dipper handle.

It is still another object of this invention to provide such a variable pitch dipper mounting that includes a control system for selectively actuating said cylinders and pistons and which control system is mounted inside the dipper handle adjacent said cylinders and pistons to minimize the length of necessary connections.

The foregoing and other objects and advantages of this invention will appear in the description which follows. In the description reference is made to the accompanying drawings which form a part hereof and in which there is shown a preferred embodiment of this invention. The preferred embodiment is described in sufiicient detail to enable those skilled in the art to practice this invention, but it is to be understood that other embodiments of the invention may be used and that structural changes may be made in the embodiments described without departing from the scope of the invention.

In the drawings:

FIG. 1 is a side view in elevation of a power shovel including the variable pitch dipper mounting of this invention;

FIG. 2 is an enlarged view in elevation of the variable pitch dipper mounting of FIG. 1;

FIG. 3 is an enlarged top plan view of the dipper mounting with elements removed for clarity;

FIG. 4 is a further enlarged view in vertical section taken in the plane of the lines 4-4 of FIG. 3;

FIG. 5 is a view in vertical section taken in the plane of the lines 5-5 of FIG. 4;

FIG. 6 is a view in vertical section taken of the lines 6-6 of FIG. 2; and

FIG. 7 is a diagrammatic view of a control system for actuating the variable pitch dipper mounting.

Referring now to FIG. 1, there is shown therein a typical power shovel to which the variable pitch dipper mounting of this invention may be applied. The power shovel includes an upper frame, designated generally by the numeral 10, mounted upon and rotatable about a lower crawler tractor 11. A boom 12 is pivotally connected at its lower end to the frame 10 and is suspended in a predetermined position by boom suspension cables 13 which connect between the upper end of the boom 12 and an A-frame 14. Alternately, the boom 12 may be suspended on boom hoist cables that function to raise and lower the boom 12 in a known manner. A dipper handle 15 operates in a saddle block 16 mounted on the boom 12. The dipper handle is extended by a thrust rope 17 and retracted by a retract rope 18 connected adjacent the forward end of the dipper handle 15.

in the plane A dipper, designated generally by the numeral 19, is connected to the forward end of the dipper handle in a manner that will be fully described hereinafter. A hoist rope 20, operating about boom point sheaves 21 connected to the end of the boom 12, is connected to lugs 22 provided on the dipper 19. Suitable power hoist equipment (not shown) of known construction and operation is employed to operate the hoist rope and the thrust and retract ropes 17 and 18, respectively, to manipulate the dipper 19.

The dipper 19 includes a front Wall 23, side walls 24 upon which the lugs 22 are mounted, and a rear wall 25. The dipper 19 is open at its top and is normally closed at its bottom by a releasable dipper door 26. The front dipper wall 23 is provided at its upper end with a plurality of teeth 27 and adjacent its lower end with heel plates 28.

Generally, the dipper 19 is pinned centrally of its rear dipper Wall to arms fabricated integral with the dipper handle 15. A pair of upper hydraulic cylinders 29 are connected between the dipper handle 15 and an upper portion of the rear dipper wall 25, and a single lower hydraulic cylinder 30 similarly is connected between the dipper handle 15 and a lower portion of the rear dipper wall 25. The specific construction of the variable pitch mechanism and mounting of the dipper 19 will now be described in detail with reference to FIGS. 2-6.

Metal plates are suitably rolled and fabricated to merge with the cylindrical dipper handle 15 and extend forwardly thereof into two spaced, parallel arms 31. The space between the arms 31 is open at the top and is closed at the bottom by a base plate 32. As shown in FIG. 6, each of the arms 31 is formed into a box section with parallel sides 33 closed at the top by a bifurcated plate 34 and at the bottom by the base plate 32. Each of the arms 31 terminates in a projecting hub 35 that is adapted to pivotally mount the dipper 19.

Each of the sides 33 of the arms 31 is provided with a portion that projects above the bifurcated plate 34 and that forms a corner to receive and mount a bearing plate 36. The pairs of bearing plates 36 are bored to receive axially restrained pins 37 that rotatably support hubs 38 attached to the piston rods 39 of the upper hydraulic cylinders 29.

A pair of spaced bearing plates 49 depend from the base plate 32 between the arms 31. The bearing plates 40 are provided with bores to receive an axially restrained pin 41 upon which is rotatably mounted a hub 42 connected to the piston rod 43 of the lower hydraulic cylinder 30.

A fabricated cage structure, designated generally by the numeral 44, is mounted on the outside of the rear dipper wall 25. The cage structure 44 includes two pairs of outer and inner vertical bearing plates 45 and 46, respectively. The bearing plates 45 and 46 project outwardly of the rear dipper wall 25 and generally horizontal transverse stiffening plates connect the bearing plates in a pair and connect the pairs of bearing plates (see FIG. 5). Each of the bearing plates 45 and 46 is provided adjacent its upper end with an upper cylinder pin bore 47 adapted to receive a pin 48 upon which is rotatably mounted a hub 49 formed integral with the upper hydraulic cylinder 29.

Below the upper cylinder pin bores 47 of each of the bearing plates 45 and 46 and substantially centrally of the top and bottom of the rear dipper wall 25, each of the bearing plates 45 and 46 is provided with a dipper pin bore 50 adapted to receive dipper pins 51 which rotatably mount the hubs 33 that project from the arms 31. Finally, the bearing plates 45 and 46 are provided adjacent their lower ends with dipper door pin bores 52 adapted to receive axially restrained pins 53 that rotatably mount the dipper door 26. The dipper door 26 may be provided with any suitable known means for releasing the door 26 upon command for dumping of the contents of the dipper 19.

A transverse plate 54 is secured between the inner bearing plates 46 toward the bottom thereof. A pair of spaced, parallel lower cylinder bearing plates 55 are secured to the underside of the plates 54 and also to the rear dipper wall 25. The lower cylinder bearing plates 55 are bored to receive a pin 56 which rotatably mounts a hub 57 formed integral with the lower hydraulic cylinder 30.

It will thus be seen that each of the pivotal connections of the cylinders 29 and 30 to the dipper handle 15 and dipper 19 and of the dipper 19 to the dipper handle 15 is formed of a cooperating clevis and hinge member, in the form of a hub, that receives an axially restrained pin.

From the description of the preferred embodiment of the dipper mounting which has thus far been given, the general operation of the mechanism can be appreciated. The dipper 19 is free to pivot in a vertical plane on the dipper pins 51 supported by the dipper handle 15 through the medium of the arms 31. Pivoting of the dipper 19 can only be accomplished under control of the upper and lower cylinders 29 and 30.

For digging through the bank of material, the dipper 19 is tilted relative to the dipper handle to offer the least resistance as the dipper is moved through the bank. Since the resistance presented by the dipper 19 will be determined by the size of the area of the dipper projected on a plane normal to the direction of motion, the front wall 23 is ideally aligned with the direction of motion through the bank with the proviso that the bottom of the front wall 23 is kept back from the bank so that the heel plates 28 will not cause a drag. Thus, at the beginning of a cut through a bank the most desirable position may have the front wall 23 tilted upwardly relative to the dipper handle 15 and as the dipper handle 15 is extended and the dipper 19 is raised by the hoist rope to move the dipper 19 through the bank it would then be desirable to rotate the front wall 23 clockwise, as viewed in FIG. 1, to present the least resistance. Such rotation would be accomplished by supplying fluid under pressure to the blank ends of the upper cylinders 29 and to the rod end of the lower cylinder 30 so that the powered extension of the upper cylinders and powered retraction of the lower cylinder 30 would provide the proper pitch to the dipper 19. In this manner the pitch of the dipper 19 can be varied as the dipper 19 moves through the bank.

For dumping of the contents of the dipper 19, the front wall 23 should be nearly vertical and this may require that the dipper be pivoted counterclockwise, as viewed in FIG. 1, to again tilt the front wall of the dipper upwardly relative to the dipper handle. This would be accomplished by supplying fluid under pressure to the rod ends of the upper cylinders 29 and to the blank end of the lower cylinder 30.

The desired positions of the dipper 19 throughout the digging and dumping cycles can be achieved without regard to the angle of inclination of the dipper handle 15.

The are through. which the dipper 19 is capable of being pivoted by the cylinders is limited by stops in the form of pressure pads. Specifically, cooperating pressure pads 58 are mounted across the front edges of the upwardly projecting portions of each pair of sides 34 of each arm 31 and across each pair of bearing plates 45 and 46. Similarly, cooperating pressure pads 59 are supported across the leading edge of a pair of pressure plates 60 which depend from the base plate 32 parallel to the bearing plates 40 and across the lower cylinder bearing plates 55. The shock of the swinging dipper door 26 is taken up by a pair of pressure plates 61 depending from each outer side 34 of the arms 31 and mounting a resilient pressure pad 62.

Referring now to FIG. 7, the control system for the upper and lower hydraulic cylinders 29 and 30, respectively, includes a hydraulic pump 63 powered by an electric motor 64 controlled by any suitable starter means 65. The pump 63 draws fluid from a reservoir 66 and delivers the fluid under pressure through a pair of output lines 67 and 68.

The pump 63 is preferably of the multiplunger variable displacement type in which a large quantity of fluid can be pumped at moderate pressures when the output of all plungers is used and a lesser quantity of fluid at higher pressures can be pumped when the output of less than all of the plungers is used. For example, if a ten plunger pump is used the outlet port connected to the output line 67 would be connected to seven of the plungers and the port connected to the output line 68 would be connected to three. When the output of all ten plungers is utilized, pressures of 1200 p.s.i. can be achieved in the system. However, when the output of seven plungers alone is used, the pump 63 is capable of working to pressures of 2000 p.s.i. although the quantity of fluid pumped is less than that which would be achieved by use of all ten plungers.

When the pump 64 is operating, the fluid exiting through the output line 67 travels through a connecting line 69 to a main control valve 70 which, when in its neutral position as illustrated in FIG. 7, diverts the fluid to connecting return lines 71, 72 and 73 which lead to the reservoir 66. The fluid exiting through the output line 68 passes through a check valve 74 and thence through the line 69 to the control valve 70 where it is diverted back to the reservoir 66.

The main control valve 70 includes solenoids 75 and 76 operating at respective ends of the valve 70. When both solenoids 75 and 76 are deenergized the valve is in the neutral position shown. When the solenoid 75 is energized the valve 70 will be shifted to the right, as viewed in FIG. 7, to connect the lines 69 and 71 directly to lines 77 and 78, respectively. When the solenoid 76 is energized the control valve 70 will be shifted to the left, as

viewed in FIG. 7, to reverse the connections and connect the line 69 to the line 78 and the line 71 to line 77.

The line 77 leads to the blank end of the lower hydraulic cylinder 30 and by a connecting line 83 to the rod ends of both of the upper hydraulic cylinders 29. The line 78 leads to a line 85 connected to the blank ends of both of the upper cylinders 29 and the rod end of the lower cylinder 30.

If it is desired to tilt the front of the dipper 19 upwardly relative to the dipper handle 15, the main control valve 70 would be placed in a position by energization of the solenoid 75 whereby there would be a direct connection of the lines 69 and 71 to the lines 77 and 78. That is, oil fed from the pump 63 would pass through the line 69, control valve 70, the line 77, and the line 83 to increase the pressure on the rod ends of the upper cylinders 29 and on the blank end of the lower cylinder 30 so that the upper cylinders 29 would retract and the lower cylinder 30 would extend to rotate the dipper 19 about its pivotal connection to the dipper handle 15. Fluid forced from the rod end of the lower cylinder 30 and from the blank ends of the upper cylinders 29 will exit through the lines 85 and 78, the control valve 70, the line 71, the line 72, and the line 73 to the reservoir 66.

If it is desired to lower the front of the dipper 19 relative to the dipper handle 15 the main control valve 70 is shifted to the left by energization of the solenoid 76 so that fluid under pressure is supplied to the line 78 and returned through the line 77.

With the pump 63 operating, if the pressure in the output line 68 exceeds 1200 p.s.i. a pressure relief valve 86 will open to vent the fluid through the lines 72 and 73 to the reservoir 66. This action will also cause the check valve 74 to close. Then, only seven pistons will be supplying fluid under pressure to the control valve 70 and fluid pressure can, therefore, be increased to 2000 p.s.i. If the pressure in the line 69 increases to more than 2000 p.s.i. due to the loads on the system caused by digging, for example, another pressure relief valve 87 will open and shunt the fluid through the lines 72 and 73 back to the reservoir 66.

Whenever the pressure relief valve 87 opens, the pressure in the system between the pump 63 and the main control valve 72 cannot exceed 2000 p.s.i.

With the control valve 70 in the neutral position a severe overload during digging through a bank causing the pressure in the cylinders to increase to 6000 p.s.i. will cause a respective one of a pair of pressure relief valves 88 to open to allow fluid to pass from the high pressure ends of the cylinders to a line 89 that connects with the line 72. Another line 90 also connects with the line 72 and leads to the inlet sides of a pair of check valves 91 having their respective outlet sides connected to the lines 77 and 78. Thus, the opening of a respective one of the pressure relief valves 88 will complete a circuit from the high pressure ends to the low pressure ends of the cylinders 29 and 30 so that fluid may pass from the high pressure end of the cylinders through the open pressure relief valve 88, the lines 89, 72, and 90, and the open check valve 91 to the low pressure ends of the cylinder. Since it is not possible to completely balance the volumes of the upper cylinders 29 with the volume of the lower cylinder 30 because of the difference in areas of rod and blank ends, this circuit is also tied in with the reservoir 66 through the line 73 which connects with both of the lines 72 and 90.

A pair of normally closed manually operated valves 92 are respectively connected across the lines 77 and 78 and a line 93 which leads to the line 89 and ultimately to the reservoir 66. The valves 92 may be employed to permit the dipper 19 to rotate without assistance from the cylinders 29 and 30 under external force during digging or otherwise. That is, if the dipper 19 is rotated upwardly relative to the dipper handle 15 to present the position ideally suited for dumping, and it is then desired to make another pass at the bank being dug after the contents of the dipper have been dumped, the valve 92 connecting the line 77 with the line 93 would be opened. If the dipper 19 is then engaged with the bank, the force on the teeth of the dipper 19 would tend to rotate the dipper clockwise, as viewed in FIG. 1, about its pivotal connection to the dipper handle 15 and fluid on the blank end of the lower cylinder 30 and on the rod ends of the upper cylinders 29 would have to be evacuated to permit such rotation. Such evacuation would be accomplished through the line 77 and the now opened manual valve 92. The dipper 19 would thus be rotated without aid of the cylinders to a position where it would engage the bottom of the bank at the maximum angle and thereafter the valve 92 would be closed and the control valve 70 would be employed to vary the pitch of the dipper 19 as the dipper moved through the bank being excavated.

Referring to FIGS. 3 and 4, the entire control system for the cylinders 29 and 30, including the motor, pump, and reservoir, is located in the dipper handle 15 in the space between the parallel arms 31. The reservoir 66 is disposed between the inner sides 33 of the arms 31 and spaced slightly above the base plate 32 and is held in such position by resilient mounting assemblies 94 located at its corners. The rear pair of mounting assemblies 94 support the reservoir 66 upon the base plate 32 and the front pair of mounting assemblies 94 support the reservoir 66 upon a transverse box section 95 that spans the arms 31. Each of the mounting assemblies 94 includes bolts 96 that connect the reservoir 66 to the respective supports and resilient washers and pads are disposed between all opposing metal surfaces in the assemblies 94 to cushion vibration and shock. The top surface of the reservoir 66 functions as a mounting plate for the motor 64, the pump 63 and a housing 97 that encloses the valves of the control system previously described.

A retract rope take-up assembly 98 is hinged at its rear end on supports provided on the top of the dipper handle 15. The rope take-up assembly 98 overlies the cylinder control system mounted between the arms 31 and is held in place by a removable pin 99 supported in bores provided in the inner sides 33 of the arms 31. In a known manner, the retract rope 18 extends through a retract rope spreader 100 and then to the take-up assembly 98 which may be pivoted upwardly after removal of the pin 99 to expose the cylinder control system for servicing of the same.

The disposition of the control system in the dipper handle 15, in addition to affording protection to the components of the control system also results in short hydraulic connections between the elements of the system and the cylinders 29 and 30. It is only necessary to run electrical connections from the cab of the power shovel to the motor 64 and to the solenoids 75 and 76 of the control valve 70. Obviously, the motor starter 65 and switches to selectively energize the solenoids 75 and 76 are conveniently located in the cab.

The central location of the pivotal mounting of the dipper 19 on the dipper handle 15 together with the disposition of the cylinders 29 and 30 above and below the pivot point of the dipper 19 results in minimizing the effect of dipper loads on the cylinders 29 and 30. This is particularly true in regard to torsional loads on the dipper 19, whether normal or excessive shock loads. The spaced pins 51 direct the twisting moments to the dipper handle 15 through the arms 31. By providing cylinders above and below the pivot point of the dipper 19 that cooperate during both their extension and retraction strokes to tilt the dipper 19 the moment arms of the cylinders about the pivot point can be kept small and accordingly smaller forces are required to be taken by the cylinders under torsional dipper loading.

Preferably, the pins 48 and the pin 56 that pivotally connect the upper and lower cylinders 29 and 30, respectively, to the dipper 19 are spaced equidistant from the pivot point of the dipper 19 so that the moment arms can be made substantially equal. This also permits the use of equal strokes in the upper cylinders 29 and the lower cylinders 30 to tilt the dipper 19.

I claim:

1. In an excavator dipper mounting, the combination comprising: a dipper handle having a forward mounting end; a dipper; means pivotally mounting said dipper on the forward mounting end of said dipper handle for pivotal movement of said dipper in a vertical plane, said mounting means being disposed between the top and bottom of said dipper; extensible and retractable power actuating means connecting said dipper handle and said dipper above and below said mounting means; and means for selectively actuating said power actuating means to vary the pitch of said dipper relative to said dipper handle.

2. In an excavator dipper mounting, the combination comprising: a dipper handle having mounting means on a forward end thereof; a dipper pivotally mounted on said mounting means for movement of said dipper in a vertical plane, the pivot point of said dipper being disposed substantially centrally of the top and bottom of said dipper; first extensible and retractable power actuating means connected between said dipper handle and said dipper above said pivot point; second extensible and retractable power actuating means connected between said dipper handle and said dipper below said pivot point; and means for selectively extending and retracting said first and second power actuating means to pivot said dipper in said vertical plane about said pivot point.

3. In an excavator clipper mounting, the combination comprising: a dipper handle having a pair of spaced arms projecting from a forward end thereof, each of said arms terminating in mounting means; a dipper including a rear wall pivotally connected to said mounting means centrally of the height of said rear Wall for movement of said dipper in a vertical plane; first extensible and retractable fluid pressure responsive means pivotally connected between said dipper handle and said rear wall at a point above the pivotal connection of said dipper to said arms; second extensible and retractable fluid pressure responsive means pivotally connected between said dipper handle and said rear wall at a point below the pivotal connection of said dipper to said arms; and control means selectively supplying fluid pressure to said fluid pressure responsive means to tilt said dipper in a selected direction relative to said dipper handle.

4. In an excavator dipper mounting, the combination comprising: a dipper handle having a forward mounting end; a dipper; means pivotally mounting said dipper on the forward mounting end of said dipper handle for pivotal movement of said dipper in a vertical plane; said mounting means being disposed substantially centrally of the top and bottom of said dipper; first extensible and retractable fluid pressure responsive means pivotally connected between said dipper handle and said dipper at a point above said mounting means; second extensible and retractable fluid pressure responsive means pivotally connected between said dipper handle and said dipper at a point below said mounting means; and fluid pressure circuit means including a control valve for selectively supplying fluid pressure to extend one of said first and second fluid pressure responsive means and to retract the other to tilt said dipper in a selected direction relative to said dipper handle.

5. In an excavator dipper mounting, the combination comprising: a dipper handle having a :pair of spaced, parallel arms projecting firom a forward end thereof; a dipp r including a rear wall; a pair of spaced, coopera ing clevis and hinge means mounted on the ends of said arms and centrally of the height of said rear wall; pins received in said clevis and hinge means to form a pivotal connection for said dipper on said dipper handle for pivotal movement of said dipper in a vertical plane; first fluid pressure responsive cylinder and piston means pivotally connected at one end to said dipper handle rearwardly of said pins and pivotally connected at its other end to said rear wall above said pins; a second fluid pressure responsive cylinder and piston means pivotally connected at one end to said dipper handle rearwardly of said pins and pivotally connected at its other end to said rear wall below said pins; and a fluid pressure control system including a control valve for selectively directing fluid pressure to extend one of said first and second cylinder and piston means and to retract the other to tilt said dipper relative to said dipper handle.

6. An excavator dipper mounting according to claim 5 wherein the pivotal connections of said first and second hydraulic cylinder and piston means to said rear wall are spaced equally above and below said pins.

7. In an excavator dipper mounting, the combination comprising: a dipper handle having a forward mounting end; a dipper including a rear wall; means pivotally mounting the rear wall of said dipper on the forward mounting end of said dipper for pivotal movement of said dipper in a vertical plane, said mounting means being disposed substantially centrally of the top and bottom of said dipper; first fiuid presure responsive cylinder and piston means pivotally connected at one end to said dipper handle reanwardly of said mounting means and pivotally connected at its other end to said rear wall above said mounting means; second fluid pressure responsive cylinder and piston means pivotally connected at one end to said dipper handle rearwardly of said mounting means and pivotally connected at its other end to said rear wall below said mounting means; and a fluid pressure control system including a motor, a pump driven by said motor and connected to supply fluid pressure to said first and second cylinder and piston means, a reservoir of fluid feeding said pump, and a control valve in the connections of said pump to said first and second cylinder and piston means, said control valve being selectively settable to direct fluid pressure to expand said first cylinder and piston means and retract said second cylinder and piston means to tilt said dipper downwardly relative to said dipper handle, to direct fluid pressure to retract said first cylinder and piston means and expand said second cylinder and piston means to tilt said dipper upwardly relative to said dipper handle, and to block the supply of fluid pressure from said pump to hold a selected tilt of said dipper.

8. In an excavator dipper mounting, the combination comprising: a dipper handle having a pair of spaced, parallel arms projecting from a forward end thereof and each terminating in hinge means; a dipper including a front wall mounting dipper teeth, side walls, and a rear wall, said rear wall having a pair of spaced clevi-ses each receiving one of said hinge means and disposed centrally of the top and bottom of said rear wall; pins received in said clevises and hinge means to form a pivotal connection for said dipper on said dipper handle for movement of said dipper in a vertical plane; first fluid pressure responsive cylinder and piston means pivotally connected at one end to said dipper handle rearwardly of said pins and pivotally connected at its other end to said rear wall above said pins; second fluid pressure responsive cylinder and piston means pivotally connected at one end to said dipper handle rearwardly of said pins and pivotally connected at its other end to said rear wall below said pins;

and a fluid pressure control system including a motor, a hydraulic pump driven by said motor and connected to said first and second cylinder and piston means to supply fluid pressure to the same, a fluid reservoir feeding said pump, and a control valve in the connection of said pump to said cylinder and piston means, said control valve being selectively sh-iftable to direct fluid pressure to expand said first cylinder and piston means and retract said second cylinder and piston means to tilt said front wall downwardly relative to said dipper handle, to direct fluid pressure to retract said first cylinder and piston means and expand said second cylinder and piston means to tilt said front wall upwardly relative to said dipper handle, and to block fluid flow from said pump to said cylinder and piston means to hold a selected position of said dipper.

9. An excavator dipper mounting according to claim 8 wherein there are a pair of spaced first cylinder and piston means each disposed above one of said arms, and said control system including said motor, pump, reservoir, and control valve is supported in said dipper handle between said arms.

No references cited.

HUGO O. SCHULZ, Primary Examiner. 

1. IN AN EXCAVATOR DIPPER MOUNTING, THE COMBINATION COMPRISING: A DIPPER HANDLE HAVING A FORWARD MOUNTING END; A DIPPER; MEANS PIVOTALLY MOUNTING SAID DIPPER ON THE FORWARD MOUNTING END OF SAID DIPPER HANDLE FOR PIVOTAL MOVEMENT OF SAID DIPPER IN A VERTICAL PLANE, SAID MOUNTING MEANS BEING DISPOSED BEWTEEN THE TOP AND BOTTOM OF SAID DIPPER; EXTENSIBLE AND RETRACTABLE POWER ACTUATING MEANS CONNECTING SAID DIPPER HANDLE AND SAID 